1. Field of the Invention
The present invention relates to a tool for loading magnetic heads onto the magnetic disk(s) of a hard disk drive.
2. Description of Related Art
Hard disk drives contain magnetic disk which spin relative to one or more magnetic heads. The magnetic heads are suspended above the surface of the magnetic disk by an actuator arm which has a magnet/coil assembly that moves the head relative to the disk. During operation, the head is supported above the surface of the disk by a high pressure air gap that is created by the rotation of the disk.
Disk drives are typically assembled by first mounting a spin motor and actuator arm assembly to a baseplate, and then attaching the magnetic disk to the motor. To provide clearance for the installation of the motor and the magnetic disk, the disk and actuator arm are initially mounted so that the magnetic head is located away from the disk. After the magnetic disk and actuator arm are installed, the head is rotated to a position above the disk. The head loading process is typically performed with some type of automated tooling, which lifts and rotates the head onto the disk.
Actuator arms typically have a large aspect ratio, resulting in an arm that is relatively flexible and weak. Consequently the arms tend to sag under the force of gravity. If multiple heads are being loaded onto the disk, the heads must be separated to assure clearance above the surface of the disk. Therefore most conventional head loading tools have means to separate and support multiple magnetic heads when the heads are being loaded onto the disk. One common type of head loading tool contains two sets of fingers which can engage the heads and move relative to each other in a scissor-like fashion. Relative movement of the fingers separates the magnetic heads, so that the heads clear the disk surface when the actuator arm is rotated above the disk. The separation of the magnetic heads must be sufficient to insure that the heads do not come into contact with the surface of the disk during the loading process. Contact between the head and the disk surface may cause damage to the head, resulting in a defective drive unit. Defective drive units lower the yield of the assembly process and invariable raise the cost of production.
The actual amount of movement by the fingers is on the order of a few thousandths of an inch. Head loading tool must therefore be very accurate. The fingers of most scissor type head loading tools extend from arms that are coupled to actuators. The actuators move the arms in opposite directions, thereby causing the fingers to separate. The arms are typically cantilevered from the actuators and are susceptible to rotational movement. Any rotational movement of the arms will effect the accuracy and repeatability of the tool. It would therefore be desirable to have a scissor type head loading tool that provides highly accurate and repeatable movement between the fingers of the arms.